In recent years the rapid expansion of the world's population coupled with the accelerated technological development of large sectors of the world has produced a dramatic increase in the demand for energy in all forms including fuels and electricity for heating, lighting, transportation and manufacturing processes. The construction of hydroelectric facilities and the development of fossil fuel resources has continued at a rapid rate, but it becomes increasingly evident for a number of reasons that these efforts are inadequate to keep pace with the demands of the growing population.
A first difficulty is the limited availability and the high cost of fuels such as oil and natural gas. Most countries in the world today do not have adequate sources of these fuels within their own boundaries and are dependent upon foreign sources.
More recently, the hope that nuclear power would soon lead to a rapid solution of the energy dilemma has been cooled by delays stemming again from environmental concerns and reservations about the safety of such plants and about the adequacy of plans for handling the radioactive wastes associated with such installations.
In the face of these growing demands and the resulting research in many fields of energy, one source of energy which is readily available to every country in the world in virtually unlimited quantities stands out. This virtually untapped source is wind energy.
The interest in this almost boundless resource and in its development and harnessing for use in homes and factories is rising as other resources dwindle. Its desirability is further enhanced by the fact that wind energy may be converted to practical use without the hazard of environmental contamination.
History does not record the date of the invention of windmills; i.e., the first land uses of wind movement, but it is known that a wind-powered water lift was used in Persia about 600 B.C. During the 12th century A.D., windmills appeared in Europe where they were used to grind grain and pump water.
A great number of different sizes and designs of windmills have been built in the past for useful purposes, but few designers have effectively utilized the laws of physics in their designs. One particular design employing a single type propeller blade vertically positioned has been used but its design negates the known principles of the old sailing ships that the more square feet of sail surface used, the more power absorbed from the wind.
Thus, it is apparent that the key factor to good wind turbine design involves the controlled exposure of the maximum amount of blade surface to the wind.
In order to increase the effectiveness of hardware necessary to harness wind movement, it is necessary to create a wind energy system which will increase the amount of surface exposed to the wind yet function at wind currents as low as 7-10 miles per hour velocity and at speeds reaching their maximum velocities. A simple and economical shielding device requiring little maintenance and upkeep activities is employed which will control the speed of the windmill causing it to operate within selected speed ranges. Such a system requires a new and novel windmill or wind turbine for effective operation with the modern day electric alternators.